1. Field of the Invention
The present invention relates to a filtering device. More particularly, the present invention relates to a filtering device for purifying water and removing oil, grease, or smoke containing oil.
2. Description of the Related Art
In the field of filtration of waste water in a septic tank, cultivating pool, etc, it is well known to use nitrobacteria to decompose organic nitrogen into ammonia, which is then oxidized into nitrate that is less toxic. The amount of organic nitrogen contained in the discharged water is reduced to achieve the purification purposes by the “biofiltration” process.
The nitrobacteria are adhesive bacteria requiring a sufficient space for propagation. The decayed and deposited sludge in a septic tank provides an environment for growth and propagation of the nitrobacteria. For purification of the waste water in the septic tank, a stirring device or pump is mounted in the septic tank for stirring or recycling the sludge, providing re-filtering and/or re-decomposition effect. However, the stirring or recycling procedure would destroy the environment for the nitrobacteria, as the sludge could not effectively gather and deposit.
Smoke and waste water discharged from the kitchen often contain oil and grease that are detrimental to the environmental hygiene and cause pollution to water. Removal of the smoke and waste water before discharge is required.